''Aetomylaeus bovinus'', also known as the bull ray, duckbill ray, or duckbill eagle ray, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of large

stingray Stingrays are a group of sea Batoidea, rays, a type of cartilaginous fish. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatidae (deepwate ...

of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Myliobatidae found around the coasts of

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

Biology and ecology

The species is

ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparity, oviparous and live-bearing viviparity, viviparous reproduction. Ovoviviparous animals possess embryos that develo ...

and reach sexual maturity at four to six years old. With a low

fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the capability to produc ...

of three to four pups per litter and a long

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregn ...

of six to 12 months (depending on the geographical zone), this species has a very sensitive life history. Very little is known concerning the ecology and behavior of ''A. bovinus''. However, it is part of the coastal marine

megafauna In zoology, megafauna (from Ancient Greek, Greek μέγας ''megas'' "large" and Neo-Latin ''fauna'' "animal life") are large animals. The precise definition of the term varies widely, though a common threshold is approximately , this lower en ...

, and with a maximum discal width (tip to tip) of , in length and weighing up to , bull rays can be considered as giants of the shallow waters. Their maximum length and very narrow depth range of exposes them to various threats. Indeed, large-body, shallow-water species are at greatest risk. Bull rays appear to be extremely rare throughout the

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

region, and its current population trend is highly suspected to be decreasing. Females are larger and heavier than males. This fish is named the bull ray because of the shape of its head and it is sometimes called the duckbill ray in

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

for its long, flat, round snout. Bull rays are " bentho-pelagic" feeders, which means that they feed on the sea floor and the water column. They feed on various invertebrates, including

crabs Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek), which typically have a very short projecting tail-like abdomen, usually hidden entirely under the thorax. Their exoskeleton is often thickened and ha ...

hermit crabs Hermit crabs are anomuran Decapoda, decapod crustaceans of the superfamily (taxonomy), superfamily Paguroidea that have adapted to occupy empty scavenged mollusc shells to protect their fragile exoskeletons. There are over 800 species of hermit c ...

squids A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also called ''squi ...

prawns Prawn is a common name for small aquatic crustaceans with an exoskeleton and ten legs (members of the order of decapods), some of which are edible. The term ''prawn''Mortenson, Philip B (2010''This is not a weasel: a close look at nature's most ...

, gastropod molluscs and

bivalve molluscs Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

. They often cause damage to clam and oyster farms.

Threats

''Aetomylaeus bovinus'' is facing various and numerous threats, from

fisheries Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish farm ...

habitat degradation Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

. As it is a

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

and semi-pelagic feeder, it is

by-catch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

by a large game of industrial or

artisanal fishing Artisanal, subsistence, or traditional fishing consists of various small-scale, low-technology, fishing practices undertaken by individual fishermen (as opposed to commercial fishing). Many of these households are of coastal or island ethnic grou ...

gear, especially pelagic trawling,

bottom trawling Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and Demersal zone, demersal trawling. Benthic tra ...

, trammel nets,

gill nets Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is ...

and

spearfishing Spearfishing is fishing using handheld elongated, sharp-pointed tools such as a spear, gig, or harpoon, to impale the fish in the body. It was one of the earliest fishing techniques used by mankind, and has been deployed in artisanal fishi ...

. Little information is available concerning this species in Africa. However, old literature refers to a discard of per year of bull rays by-caught by shrimp trawlers on the West African coast in 1988 during their late juvenile and sub/adult phase.

Conservation and status

On a global scale, ''Aetomylaeus bovinus'' is classified as Critically Endangered. The bull ray is now part of the 53% of

elasmobranchs Elasmobranchii () is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks ( division Selachii), and batomorphs (division Batomorphi, including rays, skates, and sawfish). Members of this subclass are characterised by ha ...

native to the Mediterranean Sea that are at risk of extinction and require urgent action to conserve their population and habitats. Bull rays appear to be extremely rare throughout the Mediterranean region and their current population trend is highly suspected to be decreasing (by 80% during the last 45 years according to IUCN). There are currently no species-specific measures in place. Much research is required on the bull ray's population, size, trend, habitat, ecology, and threats. In order to protect the bull ray, its habitat needs to be protected, its harvest monitored and managed, and implementation of education and awareness programs could be beneficial.

Distribution and habitat

The full distribution of the bull ray is uncertain but it is known to be found in the Mediterranean Sea, the

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...

, the eastern

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

between

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

and

Guinea Guinea, officially the Republic of Guinea, is a coastal country in West Africa. It borders the Atlantic Ocean to the west, Guinea-Bissau to the northwest, Senegal to the north, Mali to the northeast, Côte d'Ivoire to the southeast, and Sier ...

, the Atlantic from north of

Saldanha Bay Saldanha Bay () is a natural harbour on the south-western coast of South Africa. The town that developed on the northern shore of the bay, also called Saldanha, Western Cape, Saldanha, was incorporated with five other towns into the Saldanha Bay ...

in western

and round the rest of the South African coast into the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

up to

Maputo Bay Maputo () is the Capital city, capital and largest city of Mozambique. Located near the southern end of the country, it is within of the borders with Eswatini and South Africa. The city has a population of 1,088,449 (as of 2017) distributed ov ...

in southern

Mozambique Mozambique, officially the Republic of Mozambique, is a country located in Southeast Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Afr ...

, also

Zanzibar Zanzibar is a Tanzanian archipelago off the coast of East Africa. It is located in the Indian Ocean, and consists of many small Island, islands and two large ones: Unguja (the main island, referred to informally as Zanzibar) and Pemba Island. ...

and

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

. It is found between the surf zone and depths of or more and also enters

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

and

lagoons A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into '' coastal lagoons'' (or ''barrier lagoons'') a ...

. It frequents both the bottom and the surface and sometimes leaps from the water. The population size, trend, habitat, ecology and dynamic of the species remain unknown, however, like many members of the family Myliobatidae, ''Aetomylaeus bovinus'' is a potential migratory species.

References

{{Taxonbar, from=Q28598850 Aetomylaeus Fish described in 1817